乱流熱伝達を伴うクエット流れにおける大規模構造

概要

論文の詳細を見る
Direct numerical simulation of turbulent heat transfer in a plane Couette flow at Reynolds numbers of 3000 and 8600 (based on the relative wall speed and the channel width) has been performed with emphasis on a large-scale turbulence structure (LSS). Two kinds of temperature boundary conditions are employed; one is the uniform heat flux heating (UHF) and the other is the constant temperature difference between the walls (CTD). A series of DNS has been carried out for several larger computational box sizes than those of existing DNSs to examine their effect upon the LSS of the thermal field and the statistical quantities such as temperature variance. The differences caused by the boundary conditions of temperature field are discussed with respect to the LSS. For CTD, the LSS is remarkable in the outer region and is observed to be similar to that of the velocity field. Using the present largest box size of 96h×h×12.8h, the average streamwise and spanwise spacing of the LSS in both velocity and thermal fields are found to be λx = 32∼48h and λz = 2.1∼2.5h, respectively. In addition, it is concluded that the box needs to be larger than the size of the LSS in order to assess the accurate statistics such as Nusselt number.
2007-07-01